Devices for determining the drientation in space of an apparatus at a given time



Sept. 19, 1961 B. L. Y. DUBUISSON DEVICES FOR DETERMINING THEORIENTATION IN SPACE OF AN APPARATUS AT A GIVEN TIME Filed May 15, 1959V scope keptjn vertical position axis is subjeptto variations U itdStates Pa ent 4 f r. a 's,o0o,zs4'- i 1 1 DEVICES FOR DETERMINING THEORIENTATION :IN SPACE or AN APPARATUS AT A GIVEN Ber-usual Louis YvesDubuisson, Paris, France, assignor to Socit Francaise dOptique et deMcanique, Rueil- Malmais'on, France, a corporation iof France Filed May15, 1959, Ser. No. 813,548

I Claims priority, application'France, May 16, 1958 r a 3 Claims.(l'.'95-'-12.S)

. The present invention relates to devices for determining theorientation in space of an apparatus at a given time, the termorientation. being meant to indicate the angle made by a straight linefixed with respect to the apparatus with a reference straight line of afixed system of coordinates. a

The invention is more especially,. although not exclusively, concernedwith the casewhere the apparatus above referred to is a photographiccamera mounted on an aircraft to take photographs for the production ofmaps.

According to the present invention, there is mounted, on the samesupport as that carrying the above mentioned apparatus, a gyroscope therotor of which is entirely free to maintain its orientation in space,the variations of position of said apparatus with respect to the spinaxis of said rotor being indicated by any suitable means.

A preferred embodiment of the present invention will be hereinafterdescribed with reference to the accompanying drawing, given merely, byway of example and in which:

FIG. 1 shows, partly in diagrammatic elevation and partly in verticalsection, a photographic camera provided with a device according to thepresent invention to determine the'orientation in space of said camera.FIG. 2 shows an image obtained on a film with the device of FIG. 1.

In the following description, it will be supposed that photographiccamera 1 mounted on a support 2 carried by an aircraft, for instancethrough. the intermediate of resilient abutments 3 capable of absorbingvibrations, is intended to take aerial photographs for establishing amap.

In order to make this map from the aerial photographs obtained withcamera 1,'it is necessary to know the orientations of said camera at therespective times at which the pictures have been taken by the camera.

This orientation may be obtained by comparing portions of two successivepictures which overlap each other,

- but this operation requires costly and delicate optical apparatus and/or the solution of difficult analytic problems.

In ordercto simplify this operation, it has already been proposed todetermine, at the same, time as eachpicture 'is beingtaken, thedirection of the sun or that of the horizon-with respect to thephotographic camera, but the apparatus necessary to perform thisoperationis complicated and of very large dimensions. Furthermore, suchapparatus can only be used when the sun is shining or when the horizonis clearly visible over a substantial distance.

It has also been proposed, for the samepurpose, to indicatethe..relative position of the spin axis of a gyroby means of erector orbut. the orientation of such an of the speed and direction of theaircraft and the errors which r esult from such variations may be ashigh as ten minutes, which cannot be permitted for tracing a map. M V p"The device according to thepresent invention is essentiallycharacterized by the use'of at least one free gyroscope, that is to saya gyroscope the rotor of which is so mounted on its support that thespin axis of said rotor otherfequivalent means,

'eration- (such as gravity) so as scopes, which are asymmetricalaccidental accelerations.

.sensitive film 16 located in the image .flected on mirrors 10, passes IIt corresponds to the Patented Sept..19, 1961 has its. orientationpractically uninfluenced by movements of said support in space, the onlydisplacements of said axis being due to a movement of'precession, whichis linear and can be easily corrected (the errors due to the rotation ofearth, to Coriolis acceleration and to the convergence of the verticalsfrom one point to another being also corrected through known means).

Such a gyroscope may forinstance be constituted by transforming agyroscope controlled by an external acceltoeliminate the control means(such as eccentric weights) included therein.

It comprises for instance a rotor, driven at constant speed by anelectric motor fed with three-phase current or in any other way, saidrotor being connected to its cage through gimbal means mountedon ballbearings, so that said rotor can pivot about two axes perpendicular toeach other and which intersect each other at the center of gravity ofthe rotor.

Suitable means, well known in the art, may be provided to make, at thebeginning of the measurements, the plane in which the rotor is rotatingparallel to the reference plane of its casing, which. is for instancesubstantially horizontal when theaircraft is to move along a rectilinearhorizontal path. H w

The present invention does not contemplate determining the nadir pointor the horizon because such a determination would require the use ofconventional gyroand therefore sensitive to In theembodiment shown bythe drawing, cameral carries the casing 4 of such a free gyroscope(diagrammatically indicated at 5 on FIG. 1) provided with a flatmirror.6 mounted in such manner as to remain exactly in its initialorientation, close to the horizontal position, during a series ofphotographic operations.

The device includes, rigidly mounted with respect to said casing:

A source of light 7, such as a flash lamp;

A graduated scale 8 constituted by a multiplicity of cross lines; v

A first objective 9 the object focal plane of which is the plane of saidscale;

Mirrors 10 capable of bendingthe' optical axis of the apparatus so as toreduce the overall dimensions thereof;

A semi-transparent and semi-reflecting plate 11 011 the exit side ofobjective 9;

A window 12 provided in the casing 4 of the gyroscope;

A second objective 13 with mirrors 14, arranged in the same manner asmirrors 10so as to reduce thedi mensions of the whole apparatus;

And a photographic camera 15 carrying a photofocal plane of objective13. v e

These elements are mounted in such manner that the light beam fromsource 7 passes through scale 8, is rethrough objective 9 at the exit ofwhich it forms a' beam of parallel rays, passes through plate 11 andwindow 12, is reflected on mirror 6 carried by the inner gimbal ringofthe gyroscope, passes again through window 12, is reflected on plate11, passes through objective 13 ;and forms on film 16 the enlarged'image of a portion of soale'8.

. It willbe readilyunderstood that. the position of this image isdifferent accordingto the position of mirror 6 with respect to the'easing 4 of the gyroscope, that is to say according to the transverseand longitudinal'inclination of the aircraft with respectto thereference plane. central portion of the" scale only if the light beam isreflected exactly upon itself by mirror 6, that is to say if theaircraft is not inclined with respect to the initial position of themiddle plane of the gyroscope rotor.

Preferably, there is provided just in front of film 6 a being efiectedin any suitable manner, either manually, glass plate 17 carrying twolines engraved therein and or electrically, or in any other way. atright angles to each other. In ageneral manner, while I have, in theabove delnthiscase, the imagerecordedon the fi m is simil scription,disclosed what I deem to be practical and efiitto'jt at sho mbyfFIG. 2where 118 designates the-imag cient embodiments of m'yiinuention, itshould be well of scale 8 andj"19 that of the cross carried -byplate.17. }understood:that I: do -not:wish-to. belimitedixtheret as If theseimages narethoseobtained directly (the negative there 'rnight be changesmade in -the arrangeinentgdisfilmhbeing observed in the; direction ofarrow l by the position and form of the parts without departing fromdeyiceshownbyfIG, 1, andjf ithegeneraldirection of the; principle of thepresentjnyentionasvfcomprehended displacement of the ,aircraftis that ofarrow F it corr 10 within the,,scope of;the accompanying claims.

Ponds roan .ai era ielimh ng ,un era angle of What I claimjs: rad ian.ba king ardi :r g l an angle o 11,111 aysystem includinga movingzsupp jtandr pg 'fl paratus carried by saidysupport,;a:device for determining fis e o ldistanceofobjective 9 and I" that Of theorientation in space of.said apparatus at a given je iv lin ys emepe ates wit a m gnificationtime, which device comprises, in cbmbinationyagyro- ,equelto fi/f-e Itis Po ib to d te m the Sensitivity scope including a rotorlhaving a spinaxis anda-center f th ed' vi y a i abl c oic o th objectives, so as ofgravity, means for-treelymountin said' yros ope en to in p tiea lyaSensit vi y, o mroo of a g said support, said meansbeing entirelybalanced aboutfthe cours ny tab ea Lm y, b Provided to center ofgravity'of said rotor, so as to make the orientaobtaintherecording of tei g at the, Same time as tion of said rotor substantially free frominfluenceby the aerial photographs are taken. movements of said supportin space, optical-meanstor inglo a em o m rla p 7 i a d to dicating theorientation of said apparatus at agiventirne nd l g tsbeam at, thetimeWheniight penetrates intO with respect to the spin axis of said rotor,and an optical -P eg1'- Phic, cam d theop ni g 0f the system, includinga light source, means operativelyfdis- Shutter, t instance y making r aP posed with respectto .said source for'the projection of electric,cellresponsive, to said opening of the shutter and n im e, a fi stbjective, at system ofmirrors between capable of operating anyelectronic circuit to operate said objective and the latter saidmeansfordirecting said p. Itisalso possibleto make userofa microconta t'image through said objective, a semi-transparent and g z o e ctuated athe-Same me as the Shutter is semi-reflecting plate between said opticalmeans'and-first operated-so taswto close a suitableelectric circuit of.objectiverthe jmagerpassingthrough id plate ontoisai'd .lamp 7-opticalmeans', a light responsive means,'and a system In these eases,camera 15 iS n pr vi i of mirrors between saidplateandlight responsivemeans, shutter, but the-optical, devicem s P o d aga ns t the imagebeing reflected by said optical means, said plate,

.the actionof,any light,otherthan-that emi ted y lamp and thesecond-said system of. mirrors onto said lightre- According to-amodification, camera 15 is provided 0nsiv m ans, 4 with a shutter theoperation of (which is synchronized 2.. In a system including anaircraft and a photographic Withthat o t eref eemera. Scale 8 g p cameracarriedby said aircraft, a device for determining constantlyilluminated. the orientation in spaceof said camera at a given time, g-0 S l a e m fi film 16 belongs which device comprises, in combination,a. gyroscope into the main film which passes through camera 1, and the.-c1udin a rotor having a spin axis and a center of gravity, imagewhich; indicatesthe orientation of said camera is ;means for freelyrnounting said, gyroscope on said supo m in i'm i Drain a corner theponding portsaid means being entirely balanced about, the cenaefiai P gp Preferably at the S m m a i terof gravitytof-said rotor, so as tomaketheporientation PhO Og P i8 the twoimages being advantageously of saidrotorsubstantially free-from influence byymoveobtained by means of twodistinctsynchronized shutters. 5 erits of said support in space, opticalmeans including'an Such arrang ments r 1 g v n m re y y way f elementfixed in position with respect to th in axisof p said gyroscope, and anoptical system including a light 2Withtheadevicehaccording -to thepresent invention, th source, means .operatively disposed with respecttosaid variations of orientation of the successive pictures taken o r'for the projection of an image, a first objective, Yaea 1 :2 ar ndiated y, the g Obtained in a system of mirrors between said objective andthe latter camera ,15; said means'for directing said image through saidobjec- ,The ::.:d6Vie might3i i a r free gy p ,tive, a semi-transparentand semi-reflecting plate between Capable of Supplying, inazmanner-isimilar to that above said optical means and 'firstobjective,the image passing described, the variations ofsprientation of, thecamera or v vsimilar lnaa a u :in;athir plane of :reference, aninresponsive means, aaasa systemof mirrorsb'etween said stance in thehorizo Plane aXiS oiesaid'seeend plate andjlight responsive means,theimage being regymswpmbeing-ithen:h r z ntah i the s m nflected'by saidoptical means, said' late, and the second i n apl nes those in whi htheaireraft aXiS can said system of mirrors onto'said light respons vemeans. d placed transversely and longi l respectively j 3. Adeviceaccording to claim 2 in WhlCh said element AccQrd' g.1. 'j nothersmod fithe p is a light. reflecting element havinga plane refiectingsurthroughsaid plate andonto said optical means, a light meanefixed w t r sp t t ep x of e gy p face located atright angles to the spin axis of said rotorI :.-r0t0r couldbe, insteadeef fla ne' concave-01" C011- and at a fixeddistance from said rotor.

tvex ;mirror, or-asprism, .or,any other optical means. for V V e -t tiam issued from source 7 asa References Cited in thefile of this patenttion' of the relative position-ofsaid axis with respect to p.thelqasingiofhtheggymScQpe v, UNITED STATES PATENISfiThermeansifordndicating:the variations of' relative 2,047,070 HornerJuly 7, 193,6

:,orientation-of-the:axis of the gyroscope rotor, insteadof 2,273,876Lutz et al. Feb, 24; 1:942 being jopticah mightbe electricalandconsistforinstancei 2,756,653 .Ni t i Iuly 31,\.1956

.of highgaccuracy :potentiometers. ,7 I

'fIhfiiPhOtQSQHSitiVB fihIlv16-mjghhbe replaced or com- Q? PATENTSrplemented bya directobseryation device suchasa frosted 650,826 GreatBritain Mar. 7,,1951

aglassi-plat ecordinggot theyindications: visible thereon 669,959 GreatBritain Apr. 9,1952

